This invention relates to a magnetic sheet, and more particularly, to a magnetic sheet to be loaded in a magnetic sheet operating device such as an electronic or electromagnetic camera for recording magnetic signals on the sheet.
Magnetic sheets capable of recording magnetic signals representative of a still image in an annular track are known in the art. It is a common practice to accommodate such a magnetic sheet in a jacket for convenience of handling and storage. The magnetic sheet comprises a flexible substrate and a magnetic layer formed thereon. Usually, a pair of magnetic layers are coated on the opposed surfaces of the substrate partially for the purpose of preventing the sheet from warping.
On use, a magnetic sheet is mounted on a drive shaft of a magnetic sheet operating device and rotated at a high speed, for example, at 3,600 rpm. While the sheet is being rotated, a magnetic head is forced against the sheet to perform recording and reproducing operations on the sheet. A stabilizer member holds the opposite surface of the sheet to control the degree of contact between the sheet and the head. In this way, recording/reproducing operation is performed on the magnetic sheet in an electronic camera while the sheet is rotated at a high speed and pressed with a sufficient force to induce deformation. Thus the magnetic sheet must be highly durable.
For the same reason, an output of reproduction from the magnetic sheet somewhat depends on the relative location of the head and the quantity of deformation of the sheet. Output varies with the degree of contact between the head and the sheet. Thus the magnetic sheet must also have appropriate rigidity or stiffness. Because of the above-mentioned operation mode, the magnetic sheet simultaneously undergoes high speed sliding motion by rotation and deformation by bending. That is, the magnetic sheet experiences a unique mechanical fatigue of different type from those of conventional magnetic tape and disk.
There is a strong need for a magnetic sheet satisfying these considerations.